Treatment of arsenic-contaminated water using akaganeite adsorption

Abstract

The present invention comprises a method and composition using akaganeite, an iron oxide, as an ion adsorption medium for the removal of arsenic from water and affixing it onto carrier media so that it can be used in filtration systems.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Patent Application Ser. No. 60 / 460,111, entitled “Treatment of Arsenic-Contaminated Water Using Akaganeite Adsorption”, filed on Apr. 4, 2003, and the specification thereof is incorporated herein by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Grant No. DE-FC04-01AL67403 awarded by WERC / U.S. Department of Energy.BACKGROUND OF THE INVENTION[0003]1. Field of the Invention (Technical Field):[0004]The present invention relates to the use of akaganeite-coated carrier media for the adsorptive removal of arsenic from water.[0005]2. Description of Related Art[0006]Note that the following discussion refers to a number of publications by author(s) and year of publicatio...

AI Technical Summary

Benefits of technology

[0027]A primary advantage of the present invention is a reduced cost of the water treatment of small water systems.

[0028]Another advantage of the present invention is that it provides a means for point-of-use treatment for the removal of arsenic from water.

[0029]Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

[0030]The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings:

[0031]FIG. 1 shows XRD diagrams for akaganeite used in the preferred embodiment of the present invention;

[0032]FIG. 2 shows pH optimization data for the use of akaganeite in suspension;

Problems solved by technology

Arsenic contamination in surface water and groundwater systems is a result of both natural occurrences and human activities.

The economic impact of the new regulatory constraints on small communities is expected to be severe because traditional treatment technologies are not economically and technically feasible for use in the smaller systems used by such communities.

However, removal by coagulation is difficult for dissolved species of arsenic.

It has been reported that soluble arsenate is removable by adsorption to aluminum-based floc, but soluble arsenite is not removable by such a method (Gregor, 2001).

This is usually accomplished by pre-chlorination, which can lead to undesirable disinfection bi-products.

However, a driving force or difference in potential is required to create movement through the membrane.

Because of the system requirements, membrane separation can be costly.

For membranes with smaller pores, more pressure is required, and that causes an increase in energy and costs.

Although RO has reportedly removed up to 99% of total arsenic in source waters (US EPA, 2000), the system has disadvantages, which include higher volume, disposal of the concentrated discharge stream, and high operation costs.

Disadvantages of such a system include the disposal of the regenerants and spent media, and the effects on secondary water quality.

However, its application is limited to large systems where conventional flocculation followed by sedimentation may be used to remove the saturated adsorbent from water.

Images